Combing Glass

Combing is an invigorating kiln forming process and another process that is not for the faint of heart. In this process, you manipulate hot glass in a kiln by raking a stainless steel tool across the surface of the molten glass. This motion causes different colors to blend and streak in unique one-of-a-kind designing patterns.

It is another one of the hottest glass fusing projects you can do inside a kiln. This procedure can be one of the most thrilling warm glass activities. Make sure to read the safety precautions and have all the appropriate tools, clothing, and of course fusible glass that has the same COE.

Since System 96 glass melts at a lower temperature than COE 90 glass, therefore it is more suitable for this process. You can use COE 90 glass, but the temperatures will need to be higher to achieve the procedure.

Materials

Kiln

Kiln washed shelf

Ceramic fiber board (not thin fire paper)

Cleaned 3/8" to ¼" glass strips

Green, welder's safety glasses

Zetex or Kevlar gloves

Cotton clothing

Stainless Steel rod with wooden handle

Face shield

Container of water to cool rod after combing

Combing Safety Precautions:

Be sure to read and observe all the safety precautions on combing to achieve a safe project.

Turn off the kiln once the glass has reached the desired temperature. Turning off the kiln will avoid any electrical shock you might receive if the stainless steel combing rod touches any of the coils by accident.

Wear cotton clothing during the procedure. Any synthetic material can melt quickly in the high heat and cause burns to skin.

Wear a safety shield to protect your face from the high heat of the kiln.

Use a container of water that is large enough to securely hold the hot raking tool.

Preparation:

If using a long wooden handled comb that might be immersed into the kiln, it needs to be soaked in a bucket of water for at least a day. This is to ensure that the wooden handle doesn’t catch on fire during the procedure.

Prepare the glass. Be sure that it is clean and dry.

Prepare work space with needed materials. Have your gloves handy, bucket of water nearby, towel for drying the rake and your protective glasses.

The Process:

1. Kiln wash the shelf with many coats of wash. It is suggested that you put as many as 9 or more coats on the shelf. Because the kiln wash breaks down at high temps, chances are that if not properly coated the glass will stick to the shelf. Stuck glass will cause cracks, as the shelf and glass cool at different rates. Do not use thin fire paper as it will only crumble under the pressure of the dragging process, and fiber paper leaves a very coarse mark on the back of the glass. Even the kiln wash can flake off from the high heat of the procedure. Fiber board that is cut to the size of your shelf will add the best protection.

2. Cut the glass into ¼ inch by about 5 inch strips and glue them together to make a stack or slab of glass. They can be either layered on the side or laid two or three layers high.

3. Take notes of how the colors move, as you will find that different colors react differently to this process.

4. Ramp up the pieces to about 1250 degrees Fahrenheit and allow the piece to soak for about 20 minutes then continue to heat the glass until it reaches about 1640 degrees Fahrenheit, depending on your individual kiln and the COE of the glass.

5. Turn off the kiln and wearing appropriate safety apparel, open the lid.

6. Skim the top of the glass with the combing rake. Work swiftly but cautiously. You can usually pull the rod across the glass about twice before it will need to be dipped into the water to cool off the metal tip. You should only be combing the top half of the glass not going in to deep. Going to deep will cause you to pick up kiln wash in the bottom of the glass. Pull the glass a few times close the lid and allow it to heat back up and repeat the process. The glass will have the consistency of honey that has been refrigerated. Thick but still movable. Try moving the rake in different patterns across the gooey slab.

7. Flash vent the piece to approximately 1100 degrees Fahrenheit to prevent further fusing and to avoid devitrification.

8. Lengthen the annealing and cooling times slightly before bringing to room temperature

A little more information about the process:

1. Over pulling will make the colors appear muddy and not as desired. Just pull a few times and allow the piece to heat up more before raking the glass any more.

2. Use the comb to pop any bubbles that might appear.

3. You need to have a plan when opening the kiln. Don’t just stand and look at the glass, but move swiftly.
4. Try using a long stainless steel barbecue fork with the end bent as a raking tool.

5. Try using iridescent glass as a base with the iridescent side down, which will release from the kiln wash easier.

6. Use 2 combs to pull and push the glass strips at the same time.

7. If the glass starts to stick to the rod, hold the rod above the glass for a few seconds. This will allow the glass to cool slightly. Twist it a little to one side and the glass should break off. Place in water container.

8. Allow any glass stuck to the rod to cool before removing it from the kiln. You don’t want to drip molten glass on the floor. Then place the tip of the rod in water to cool.
9. Dry the rod before the next raking motion.

10. You have a very limited time to do the combing, 10-15 seconds if you lit the lid all the way.

11. Dip your tip in water between pulls otherwise if the metal gets too hot it sticks to the glass.

12. When it feels really hard to pull or rake the glass, put the lid back on and allow the kiln and glass to heat up again. Repeat until you have reached your desired appearance.